1. Field of the Invention
This invention is concerned with a cell unit for observing an electrophoresis, more particularly with a measurement or measuring cell unit for observing an electrophoresis of living cells by means of a microscope.
2. Description of the Prior Art
Apparatus adapted to measure the velocities of minute or fine particles such as living cells in a liquid specimen under the effect of an electric field and calculate the electrophoretic mobility of the particles have been well-known and generally referred to as a living cell electrophoresis apparatus or electrophoretic apparatus for living cells. Upon observing or measuring the velocities or the electrophoretic mobility or mobilities of the particles in the liquid specimen flow or turbulence of the liquid specimen which affects the movement of particles to cause errors in observed or measured values has to be eliminated as much as possible.
In view of the above, the measurement cell system in the electrophoretic apparatus generally comprises a unit including a measurement cell, electrodes for giving the electric potential gradient to the liquid specimen in the measurement cell, diaphragms formed by substantially rigidly supported membranes, valves for sealing the specimen in the measurement cell (hereinafter referred to as sealing valves) and so on. The diaphragm formed by the substantially rigidly supported membrane serves for preventing the gas or bubbles produced at surfaces of the electrodes in the course of the electrode reaction from entering the measurement cell. The diaphragm is made of a substantially rigidly supported porous membrane such as an ion-exchange membrane or a dialysis membrane and, in conventional measurement cell units, have been designed to be secured by an adequate means such as a perforated plate so that they may not be bent nor displaced. Each of the sealing valves which are disposed in ducts as conduits for introducing and discharging the liquid specimen into and from the measurement cell generally comprises a cock made of glass, or a sluice valve made from teflon (polytetrafluoroethylene). In the measurement of the velocities of the particles in the liquid specimen in the electric field by using the measurement cell unit of this type, the stability or reproducibility of the measurement is largely dependent on the way of sealing or confining the liquid specimen in the measurement cell. Accordingly, those valves having a good sealing performance and not causing the flow or turbulence of the liquid specimen to be sealed upon closing operation of the valves have been demanded for as the sealing or confining valve for use in the measurement cell unit for electrophoresis. In this viewpoint, a pinch valve or a pinch cock designed to nip or pinch a flexible or resilient tube to close the liquid passage in the tube has been considered unsuitable for the sealing valve, because it deforms the flexible tube upon pinching to affect the liquid specimen to be sealed, that is, it causes the undesired flow or turbulence of the liquid specimen due to the change in the inner pressure of the tube upon sealing or confining the liquid specimen in a limited space including the space in the measurement cell.
Although the conventional valve such as the glass cock and the teflon sluice valve do not cause the sealed liquid specimen to move or flow, the sealing performances of these valves are not adequate but the sealing performance or degree of the sealing of the valves fluctuates on varies on every opening and closing operation of the valves, and thus desired stability can not always be obtained in the measurements or observations of the living cell electrophoresis.
In order to overcome the foregoing problems cause by the conventionally used valves in the measurement cell unit, the inventors have chosen a pinch valve having a good sealing performance as the sealing valve while making an attempt to solve the problem of the flow of the liquid specimen attributable to the use of the pinch valve by the improvement in other part of the cell unit.